Interleukin 11-induced microRNAs as functional mediators and circulating biomarkers of cardiac fibrosis

BackgroundCardiac fibrosis can be triggered by several pathologies, including ischemic heart disease and aortic stenosis (AS). Cardiac fibrosis is brought about by uncontrolled extracellular matrix (ECM) deposition by myofibroblasts. Interleukin-11 (IL-11) has been firmly demonstrated to be a major trigger of multi-organ fibrosis. However, the molecular mechanisms underpinning IL-11-induced fibrosis requires further characterisation. Recent studies indicate that microRNA (miRNA) dysregulation contributes to the pathogenesis of cardiac fibrosis and can be targeted therapeutically. In this study, we explored the hypothesis that miRNAs act as downstream effectors of IL-11-induced cardiac fibrosis. Moreover, we investigated the translational potential of IL-11-regulated miRNAs as circulating biomarkers of cardiac fibrosis in AS patients. Methods and ResultsUsing computational approaches, we identified miRNA-497-5p and miRNA-27b-5p as potential new downstream profibrotic effectors of IL-11 in fibroblasts. We next confirmed that both miRNAs increased in healthy rat CF stimulated with IL-11 and in CF derived from post-infarction failing hearts. At the functional level, miRNA-497-5p and miRNA-27b-5p inhibition indirectly reduced the mRNA expression of collagen 1 (Col1a1). Conversely, transfection of CFs with mimics for each of the two miRNAs promoted fibroblast-to-myofibroblast transition and increased Col1a1 levels. We provided evidences that miRNA-27b-5p and miRNA-497-5p converge to promote hypoxia-inducible factor 1 signalling, by targeting its regulator EGLN (PHD) family members. The clinical relevance of our findings was confirmed using left ventricle (LV) specimens obtained from surgical patients with AS. The miRNA-27b-5p and miRNA-497-5p measured in the LV, peripheral plasma and plasma extracellular vesicles correlated with the severity of LV fibrosis, indicating these miRNAs potential as new circulating biomarkers of cardiac fibrosis. ConclusionsIn this study, we have newly identified the potential value of miRNA-27b-5p and miRNA-497-5p as actionable biomarkers of the profibrotic response to IL-11 in the heart. Future studies should validate the translational potential of the miRNAs as new clinical biomarkers and therapeutic targets.